/*
 * Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
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 *
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 *
 *
 *
 *
 */

package java.security;

import java.io.*;
import java.security.cert.CertPath;

/**
 * This class encapsulates information about a code signer.
 * It is immutable.
 *
 * @author Vincent Ryan
 * @since 1.5
 */

public final class CodeSigner implements Serializable {

  private static final long serialVersionUID = 6819288105193937581L;

  /**
   * The signer's certificate path.
   *
   * @serial
   */
  private CertPath signerCertPath;

  /*
   * The signature timestamp.
   *
   * @serial
   */
  private Timestamp timestamp;

  /*
   * Hash code for this code signer.
   */
  private transient int myhash = -1;

  /**
   * Constructs a CodeSigner object.
   *
   * @param signerCertPath The signer's certificate path. It must not be {@code null}.
   * @param timestamp A signature timestamp. If {@code null} then no timestamp was generated for the
   * signature.
   * @throws NullPointerException if {@code signerCertPath} is {@code null}.
   */
  public CodeSigner(CertPath signerCertPath, Timestamp timestamp) {
    if (signerCertPath == null) {
      throw new NullPointerException();
    }
    this.signerCertPath = signerCertPath;
    this.timestamp = timestamp;
  }

  /**
   * Returns the signer's certificate path.
   *
   * @return A certificate path.
   */
  public CertPath getSignerCertPath() {
    return signerCertPath;
  }

  /**
   * Returns the signature timestamp.
   *
   * @return The timestamp or {@code null} if none is present.
   */
  public Timestamp getTimestamp() {
    return timestamp;
  }

  /**
   * Returns the hash code value for this code signer.
   * The hash code is generated using the signer's certificate path and the
   * timestamp, if present.
   *
   * @return a hash code value for this code signer.
   */
  public int hashCode() {
    if (myhash == -1) {
      if (timestamp == null) {
        myhash = signerCertPath.hashCode();
      } else {
        myhash = signerCertPath.hashCode() + timestamp.hashCode();
      }
    }
    return myhash;
  }

  /**
   * Tests for equality between the specified object and this
   * code signer. Two code signers are considered equal if their
   * signer certificate paths are equal and if their timestamps are equal,
   * if present in both.
   *
   * @param obj the object to test for equality with this object.
   * @return true if the objects are considered equal, false otherwise.
   */
  public boolean equals(Object obj) {
    if (obj == null || (!(obj instanceof CodeSigner))) {
      return false;
    }
    CodeSigner that = (CodeSigner) obj;

    if (this == that) {
      return true;
    }
    Timestamp thatTimestamp = that.getTimestamp();
    if (timestamp == null) {
      if (thatTimestamp != null) {
        return false;
      }
    } else {
      if (thatTimestamp == null ||
          (!timestamp.equals(thatTimestamp))) {
        return false;
      }
    }
    return signerCertPath.equals(that.getSignerCertPath());
  }

  /**
   * Returns a string describing this code signer.
   *
   * @return A string comprising the signer's certificate and a timestamp, if present.
   */
  public String toString() {
    StringBuffer sb = new StringBuffer();
    sb.append("(");
    sb.append("Signer: " + signerCertPath.getCertificates().get(0));
    if (timestamp != null) {
      sb.append("timestamp: " + timestamp);
    }
    sb.append(")");
    return sb.toString();
  }

  // Explicitly reset hash code value to -1
  private void readObject(ObjectInputStream ois)
      throws IOException, ClassNotFoundException {
    ois.defaultReadObject();
    myhash = -1;
  }
}
